This invention relates generally to synthetic sheet composites, and more particularly concerns a durable, tear resistant synthetic sheet composite having paper-like aesthetic qualities.
Envelopes used by couriers and other packages which are traditionally made of paper are often subjected to conditions in which paper packaging will likely fail. Such envelopes and packages may be subjected to moisture or to tearing and abrasion during handling and shipment. Most paper products simply cannot undergo the kinds of abuse which courier envelopes and other such packages encounter.
The only paper-like product presently available for such commercial applications is a linear polyethylene sheet material sold under the trademark TYVEK by DuPont of Wilmington, Del. TYVEK is flash-spun from a solvent at 200.degree. C. and 1,000 pounds per square inch (psi). The flash spinning attenuates and fractures the polyethylene into continuous fibrils that are collected on a moving belt and then thermally bonded to each other by a heated supercalender. Such material, however, while having adequate tensile strength and initial tear resistance, is easily torn once material has been slit or torn.